So that an electrical drive, for example, a three-phase-current motor, can be used in applications or systems as a safety-related component, safety relays, motor protective switches, or motor protective relays and fuses are necessary, which can move the drive into a safe state. Safety relays are used to turn off an electric drive as soon as an emergency shutdown switch, protective door switch, or two-hand switch has been activated. Motor protective switches have the task, for example, if there is a thermal overload, of moving the drive into a safe state with the help of bimetals.
A disadvantage in such safety measures is that the components have large space requirements and considerable wiring complexity. This leads to, among other things, high costs and significant maintenance expense. In addition, the electromagnetic contactors that are used exhibit contact wear. In addition, there is the risk that, in the implementation of a system with safety-related components, the motor protective switches and the safety relays will be connected incorrectly to the safety-related components, or defective components will be used, so that the system, the electric drive, and/or operating personnel can be endangered due to incorrect operation.